Embodiments of the inventive concept described herein relate to a lithium-air battery catalyst having a 1D polycrystalline tube structure of a ruthenium oxide-manganese oxide complex and a manufacturing method thereof, and more particularly, relate to a lithium-air battery catalyst including a ruthenium oxide-manganese oxide complex tubes structure having a core fiber-shell patterned nanotubes structure or a double walls patterned composite double tubes structure, and a manufacturing method thereof.
In a rapid increase of worldwide energy demand along development of industrial technology, being rid of environmental problems due to fossil fuels as current main energy supply sources, many interests and demands are focusing on exploitation of production and storage systems for eco-friendly alternative energy. Lithium-air batteries are coming to the forefront as the development-promising new generation energy storage devices owing to their theoretical energy density equal to or 10 times higher than that of current lithium-ion batteries, and their eco-friendliness. Especially, because the lithium-air battery utilizes oxygen as a reaction fuel for an air electrode (or cathode) and utilizes a lithium metal as an anode, it has high theoretical energy density that is comparable to that of current gasoline fuel. Therefore, the lithium-air batteries are being in the limelight as technology for commercialization of electric vehicles.
In activating a lithium-air battery, oxygen of air meets lithium ions in an electrolyte and forms a solid lithium peroxide during a discharge on an air electrode (oxygen reduction reaction; O2(g)+2Li++2e−->Li2O2(s)), and the lithium peroxide is decomposed again into oxygen and lithium ions during a charge (oxygen evolution reaction; LiO2(s)->O2(g)+2Li++2e−).
However, a large amount of energy loss is accompanied on an electrochemical reaction with lithium and oxygen and thereby the battery becomes remarkably lower in lifetime characteristics. Accordingly, to prevent energy loss during such a discharge and a charge, some studies have proceeded for developing an OER and ORR active catalysts to be employed for air electrodes.
Nowadays many studies for varieties of catalysts are still in progress, having been advanced in enhancing the battery efficiency through development of air electrodes where carbon materials are combined with catalysts based on precious metals, such as Au, Ag, Pt, Pd, Ru, and Ir, or based on transition metal oxides such as MnO2, Mn2O3, CO3O4, CuO, Fe2O3, LaMnO3, MnCo2O4, Ba0.5Sr0.5Co0.2Fe0.8O3. Activity of catalysts is dependent on varieties of element technologies such as manufacturing method, surface structure, crystallinity, oxidation number, and specific surface area. In the meantime, there are also progressing developments of nanostructures for strengthening activity of catalysts and efforts for finding catalytic materials having good bifunctional reactivity such as OER and ORR.